using RemoteFrameBuffer.Common;
using System.Data;
using System.Text;

namespace RemoteFrameBuffer.Client
{
    public abstract class RemoteFrameBufferClientProtocol
    {
        public enum RfbClientProtocolPhase
        {
            None,
            Constructed,
            Handshake,
            HandshakeDone,
            Initialization,
            InitializationDone,
            Listening,
            Stopped
        }

        private Task? backgroundWorker;
        private CancellationTokenSource? cancellationTokenSource;
        private Timer? _timer;
        public RfbClientProtocolPhase Phase { get; protected set; } = RfbClientProtocolPhase.None;

        protected readonly Stream vncStream;
        public abstract RfbProtoVersion Version { get; }
        public RemoteFramebufferSecurityType SecurityType { get; protected set; } = RemoteFramebufferSecurityType.Invalid;

        private RgbFrameBuffer? _frameBuffer;

        public RemoteFrameBufferClientProtocol(Stream s)
        {
            this.vncStream = s;
        }

        public abstract void Handshake(CancellationToken token);
        public void Initialization(CancellationToken token)
        {
            if (this.Phase != RfbClientProtocolPhase.HandshakeDone)
            {
                throw new InvalidOperationException("In wrong phase when calling Initialization");
            }
            this.Phase = RfbClientProtocolPhase.Initialization;
            Byte[] buf;
            // ClientInit: Ask for a shared session; should probably make it configurable later
            this.vncStream.WriteByte((Byte)0);
            // ServerInit
            buf = new Byte[24];
            CancellationTokenSource readTimeout = new CancellationTokenSource(TimeSpan.FromSeconds(5));
            CancellationTokenSource readTokenSource = CancellationTokenSource.CreateLinkedTokenSource(token, readTimeout.Token);
            this.vncStream.ReadExactlyAsync(buf, 0, buf.Length, readTokenSource.Token).AsTask().Wait();
            if (BitConverter.IsLittleEndian)
            {
                Array.Reverse(buf, 0, 2);// fb width
                Array.Reverse(buf, 2, 2);// fb height
                Array.Reverse(buf, 8, 2);// red-max
                Array.Reverse(buf, 10, 2);// green-max
                Array.Reverse(buf, 12, 2);// blue-max
                Array.Reverse(buf, 20, 4);// name mength
            }
            UInt16 width = BitConverter.ToUInt16(buf, 0);
            UInt16 height = BitConverter.ToUInt16(buf, 2);
            Console.Error.WriteLine($"FB: {width}x{height} {buf[5]}({buf[4]}) {(buf[6] == 0 ? "LE" : "BE")} {(buf[7] == 0 ? "pallette" : "TrueColor")}");
            this._frameBuffer = new(width, height);
            UInt32 nameLen = BitConverter.ToUInt32(buf, 20);
            String name;
            if (nameLen > 0)
            {
                buf = new Byte[nameLen];
                readTimeout = new CancellationTokenSource(TimeSpan.FromSeconds(5));
                readTokenSource = CancellationTokenSource.CreateLinkedTokenSource(token, readTimeout.Token);
                this.vncStream.ReadExactlyAsync(buf, 0, buf.Length, readTokenSource.Token).AsTask().Wait();
                name = Encoding.UTF8.GetString(buf);
                Console.Error.WriteLine($"Name: {name}");
            }

            this.Phase = RfbClientProtocolPhase.InitializationDone;
        }

        public Task StartListener(CancellationToken token)
        {
            if (this.Phase == RfbClientProtocolPhase.InitializationDone)
            {
                this.cancellationTokenSource = CancellationTokenSource.CreateLinkedTokenSource(token);
                this.Phase = RfbClientProtocolPhase.Listening;
                Console.Error.WriteLine("VNC client starting");
                this.backgroundWorker = new Task(this.Listener, this.cancellationTokenSource.Token);
                this.backgroundWorker.ContinueWith(this.ListenerStopped);
                this.backgroundWorker.Start();
                this._timer = new(this.FrameUpdateRequest, null, TimeSpan.FromMilliseconds(100), TimeSpan.FromMilliseconds(2000));
                return this.backgroundWorker;
            }else
            {
                throw new InvalidOperationException("In wrong phase when calling StartListener");
            }
        }

        protected void FrameUpdateRequest(Object? si)
        {
            Console.Error.WriteLine("Requesting update");
            Byte[] w = BitConverter.GetBytes(this._frameBuffer!.Width);
            Byte[] h = BitConverter.GetBytes(this._frameBuffer!.Height);
            if (BitConverter.IsLittleEndian)
            {
                Array.Reverse(w);
                Array.Reverse(h);
            }
            Byte[] buf = new Byte[]{ 3, 1, 0, 0, 0, 0, w[0], w[1], h[0], h[1] };
            this.vncStream.Write(buf);
        }

        private void ListenerStopped(Task t)
        {
            this.Phase = RfbClientProtocolPhase.Stopped;
            Console.Error.WriteLine("VNC client exited");
            this.backgroundWorker = null;
        }

        public void StopListener()
        {
            if (this.Phase != RfbClientProtocolPhase.Listening)
            {
                throw new InvalidOperationException("In wrong phase when calling StopListener");
            }
            if (this.backgroundWorker != null)
            {
                this.cancellationTokenSource!.Cancel();
                this.backgroundWorker.Wait();
            }
        }

        private void Listener()
        {
            Byte[] buf = new Byte[1];
            while (!this.cancellationTokenSource!.Token.IsCancellationRequested)
            {
                this.vncStream.ReadExactlyAsync(buf, 0, buf.Length, this.cancellationTokenSource.Token).AsTask().Wait();
                //Console.Error.WriteLine($"<== ServerMessage {buf[0]}");
                this.HandleServerMessage(buf[0]);
            }
        }

        protected void HandleServerMessage(Byte code)
        {
            switch (code)
            {
            case 0:
                this.ServerMsg_FramebufferUpdate();
                break;
            case 1:
                this.ServerMsg_SetColourMapEntries();
                break;
            case 2:
                this.ServerMsg_Bell();
                break;
            case 3:
                this.ServerMsg_ServerCutText();
                break;
            default:
                throw new NotSupportedException($"Unknown server message ID: {code}");
            }
        }

        protected void ServerMsg_FramebufferUpdate()
        {
            Byte[] buf = new Byte[3];
            this.vncStream.ReadExactlyAsync(buf, 0, buf.Length, this.cancellationTokenSource!.Token).AsTask().Wait();
            if (BitConverter.IsLittleEndian)
            {
                Array.Reverse(buf, 1, 2);
            }
            UInt16 rectangles = BitConverter.ToUInt16(buf, 1);
            Console.Error.WriteLine($"<<= FramebufferUpdate ({rectangles})");
            for (Int32 i = 0; i < rectangles; i++)
            {
                buf = new Byte[12];
                this.vncStream.ReadExactlyAsync(buf, 0, buf.Length, this.cancellationTokenSource!.Token).AsTask().Wait();
                if (BitConverter.IsLittleEndian)
                {
                    Array.Reverse(buf, 0, 2);
                    Array.Reverse(buf, 2, 2);
                    Array.Reverse(buf, 4, 2);
                    Array.Reverse(buf, 6, 2);
                    Array.Reverse(buf, 8, 4);
                }
                UInt16 x = BitConverter.ToUInt16(buf,0);
                UInt16 y = BitConverter.ToUInt16(buf,2);
                UInt16 w = BitConverter.ToUInt16(buf,4);
                UInt16 h = BitConverter.ToUInt16(buf,6);
                UInt32 encoding = BitConverter.ToUInt32(buf,8);
                Console.Error.WriteLine($"RECT {w}x{h} @ {x}:{y}, as {encoding}");
                switch (encoding)
                {
                case 0:
#warning I'm straight up assuming 24-bit little endian RGB sent as padded 32bit pixels, ignoring what format the server specified
                    Int32 bytes = w * h * 4;
                    buf = new Byte[bytes];
                    this.vncStream.ReadExactlyAsync(buf, 0, buf.Length, this.cancellationTokenSource!.Token).AsTask().Wait();
                    RgbPixel[][] px = new RgbPixel[h][];
                    for (Int32 row = 0; row < h; row++)
                    {
                        px[row] = new RgbPixel[w];
                        for (Int32 col = 0; col < w; col++)
                        {
                            Int32 off = (row*w*4)+(col*4);
                            px[row][col] = new RgbPixel() { Red = buf[off+2], Green = buf[off+1], Blue = buf[off] };
                        }
                    }
                    this._frameBuffer!.SetRegion(px, 0, 0, w, h, x, y);
                    break;
                default:
                    throw new NotImplementedException();
                }
            }
            this._frameBuffer!.SaveBitmap($"{DateTime.Now:yyyyMMdd-HHmmss}.bmp");
        }

        protected void ServerMsg_SetColourMapEntries()
        {
            throw new NotImplementedException();
        }

        protected void ServerMsg_Bell()
        {
            throw new NotImplementedException();
        }

        protected void ServerMsg_ServerCutText()
        {
            throw new NotImplementedException();
        }
    }
}